科研之友
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摘要
Several peptide families, including insect antimicrobial peptides, plant protease inhibitors, and ion channel gating modifiers, as well as blockers from scorpions, bear a common CS alpha beta scaffold. The high structural similarity between two peptides containing this scaffold, drosomycin and a truncated scorpion beta-toxin, has prompted us to examine and compare their biological effects. Drosomycin is the most expressed antimicrobial peptide in Drosophila melanogaster immune response. A truncated scorpion beta-toxin is capable of binding and inducing conformational alteration of voltage-gated sodium channels. Here, we show that both peptides (i) exhibit anti-fungal activity at micromolar concentrations; (ii) enhance allosterically at nano-molar concentration the activity of Lqh alpha IT, a scorpion alpha toxin that modulates the inactivation of the D. melanogaster voltage-gated sodium channel (DmNa(v)1); and ( iii) inhibit the facilitating effect of the polyether brevetoxin-2 on DmNa(v)1 activation. Thus, the short CS alpha beta scaffold of drosomycin and the truncated scorpion toxin can maintain more than one bioactivity, and, in light of this new observation, we suggest that the biological role of peptides bearing this scaffold should be carefully examined. As for drosomycin, we discuss the intriguing possibility that it has additional functions in the fly, as implied by its tight interaction with DmNa(v)1.
- 出版日期2009-8-28
